Enhanced electromagnetic wave absorption performance of SiCN(Fe) fibers by in-situ generated Fe3Si and CNTs

Polymer‐derived Co2Si(Co)/SiCN composite ceramics with tunable microwave absorption properties

“…Electric energy and magnetic energy will convert. When the magnetic energy radiates outward, μ′′ and tan δμ become negative 18 . Additionally, there are some resonance peaks in 2–18 GHz for Co 2 Si(Co)/SiCN ceramics, which can be attributed to the existence of natural resonance and exchange resonance.…”

“…According to XRD results, graphite carbon and Si 2 N 2 O phases would be separated from amorphous SiCN ceramics earlier, in which oxygen comes from the operation process or raw materials. The formation of Si 3 N 4 can be attributed to the decomposition of Si 2 N 2 O into Si 3 N 4 and SiO steam 18 . The crystalline SiC may be formed by the reaction of Si 3 N 4 with C, or by the reaction of SiO steam with CO gas, as presented in the following formula 24–26 : $$$$\begin{equation}3S{i}_2{N}_2{\mathop{\rm O}\nolimits} (s) \to S{i}_3{N}_4(s) + 3Si{\mathop{\rm O}\nolimits} (g) + {N}_2(g)\end{equation}$$$$ $$$$\begin{equation} 3S{i}_{2}{N}_{2}\mathrm{O}(s)+\mathrm{N}_2(g)+3C(s)\to 2S{i}_{3}{N}_{4}(s)+3C\mathrm{O}(g) \end{equation}$$$$ $$$$\begin{equation}{\mathop{\rm Si}\nolimits} {\mathop{\rm O}\nolimits} (g) + 3CO(g) \to {\mathop{\rm SiC}\nolimits} (s) + 2C{O}_2(g)\end{equation}$$$$ …”

“…However, their microwave absorption properties can be improved by adding dielectric or conducting materials, such as SiC nanoparticle/SiBCN composite ceramics, 13 Carbon nanotubus (CNTs)/SiCN, 14 Reduced graphene oxide (RGO)‐SiBCN composites, 15 RGO‐SiCnw/SiBCN 16 . Additionally, previous studies have proved that Fe, Co, and Ni have good catalysis, so introducing transition metals (Fe, Ni , and Co) into precursor ceramics has attracted increasing attention 17,18 . The introduction of transition metals (Fe, Ni, and Co) will not only make the material have magnetic loss, but also catalyze the formation of nanowires to enhance conduction loss.…”

Tuning Dielectric Loss of SiO2@CNTs for Electromagnetic Wave Absorption

“…The reflection loss of ZnFe 2 O 4 @CNT/PVDF composite film prepared by Li et al was −54.5 dB, with a matching thickness of 2.4 mm [12]. Gong et al reported SiCN(Fe) fibers with an R L of −47.64 dB and the effective absorption bandwidth of 4.28 GHz [13].…”

“…Carbonaceous materials such as graphene, carbon nanotubes (CNTs) and carbon nanofibers have attracted great attention because of their low mass density, good mechanical and chemical stability and high surface areas [1][2][3][4][5][6][7][8][9]. Carbon nanotubes have received extensive attention and in-depth studies in the field of EMW absorption due to their tubular structure suitable for electron transport, their light weight and good electrical conductivity [10][11][12][13][14][15][16][17]. For example, Lv et al encapsulated Fe/Fe 3 C nanoparticles (NPs) into N-doped CNTs (NCNTs) and obtained the result that the sample had a reflection loss (R L ) of −46.0 dB and a thickness of 4.97 mm at 3.6 GHz [10].…”